1. Technical Field
The present invention relates to wireless communication methods and systems and, more particularly, to allocation of channel resources and beam pattern selection.
2. Description of the Related Art
Beamforming is supported by certain Orthogonal Frequency-Division Multiple Access (OFDMA) standards, where multiple beam patterns (one per client) are applied in the digital signal space for each client scheduled in the frame. This is called user-level beamforming and the beam patterns are only allowed for application to the data payload in the frame. Another limitation of user-level beamforming is that the standards only specify a limited number of antenna elements, limiting the directionality of beam patterns. External beamforming (or frame-level beamforming) on the other hand applies a beam pattern (common to all clients in the frame) at the radio frequency (RF) level on the entire frame, including the preamble and control payload. In addition, the number of antenna elements is not limited since this is an application of beamforming that is agnostic of the standards support. This permits for the use of a larger number of antenna elements than what is defined in the standards and hence, enables more directional (i.e., focused) beams.
In OFDMA systems, the base stations (e.g., femtocells) carry out the scheduling for both the downlink and the uplink. In the uplink, the clients indicate the amount of data in their transmission buffers to their base station. The base station then allocates sufficient resources for each client. This scheduling is traditionally carried one frame after another (called per-frame scheduling). On the contrary, batch scheduling aggregates client requests over multiple frames and performs the resource allocation accordingly. Batch scheduling allows for more careful optimization at the base station and also reduces the signaling overhead for uplink scheduling requests from clients.